High-frequency vibration analysis of LiTaO3 piezoelectric plates excited by lateral electric fields produced by surface electrodes under viscous liquid loadings for sensing

Abstract

In this work, the coupled thickness-shear and flexural vibrations of the LiTaO3 piezoelectric plates excited by lateral electric fields produced by surface electrodes under viscous liquid loadings are modeled and analyzed based on Mindlin’s plate theory. The influences of liquid properties on the admittance characteristics and frequency shifts of the piezoelectric bulk acoustic wave devices operate in the lateral field excitation (LFE) mode are examined. In addition, the effects of the structure parameters, such as the electrode gap width, electrode/plate mass ratio and the electrode width, on the frequency sensitivity are investigated. It is shown that with the increasing electrode/plate mass ratio R, the sensitivities of the device on liquid viscosity and density increase first and then decrease, there is a maximal sensitivity when R is with a certain value. The varying trends of the frequency shifts with various liquid properties and sensitivities with various structural parameters are verified by the FEM simulations. The results are crucial to obtain good vibration characteristics and sensitivities for liquid-phase LFE piezoelectric sensors by using LiTaO3 piezoelectric crystals.